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Tidy up pmap_copy(). Notably, deindent the innermost loop by making a

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simple change to the control flow.  Replace an unnecessary test by a
KASSERT.  Add a comment explaining an obscure test.

Reviewed by:	kib, markj
MFC after:	3 weeks
Differential Revision:	https://reviews.freebsd.org/D20812
This commit is contained in:
alc 2019-07-01 22:00:42 +00:00
parent 950e6c68ee
commit 46619874b1
1 changed files with 49 additions and 56 deletions
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105
sys/amd64/amd64/pmap.c
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@ -6345,18 +6345,18 @@ pmap_unwire(pmap_t pmap, vm_offset_t sva, vm_offset_t eva)
*
* This routine is only advisory and need not do anything.
*/
void
pmap_copy(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_t dst_addr, vm_size_t len,
vm_offset_t src_addr)
{
struct rwlock *lock;
struct spglist free;
vm_offset_t addr;
vm_offset_t end_addr = src_addr + len;
vm_offset_t va_next;
pml4_entry_t *pml4e;
pdp_entry_t *pdpe;
pd_entry_t *pde, srcptepaddr;
pt_entry_t *dst_pte, PG_A, PG_M, PG_V, ptetemp, *src_pte;
vm_offset_t addr, end_addr, va_next;
vm_page_t dst_pdpg, dstmpte, srcmpte;
pt_entry_t PG_A, PG_M, PG_V;
if (dst_addr != src_addr)
return;
@ -6375,6 +6375,7 @@ pmap_copy(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_t dst_addr, vm_size_t len,
if (pmap_emulate_ad_bits(dst_pmap))
return;
end_addr = src_addr + len;
lock = NULL;
if (dst_pmap < src_pmap) {
PMAP_LOCK(dst_pmap);
@ -6389,11 +6390,6 @@ pmap_copy(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_t dst_addr, vm_size_t len,
PG_V = pmap_valid_bit(dst_pmap);
for (addr = src_addr; addr < end_addr; addr = va_next) {
pt_entry_t *src_pte, *dst_pte;
pml4_entry_t *pml4e;
pdp_entry_t *pdpe;
pd_entry_t srcptepaddr, *pde;
KASSERT(addr < UPT_MIN_ADDRESS,
("pmap_copy: invalid to pmap_copy page tables"));
@ -6435,7 +6431,8 @@ pmap_copy(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_t dst_addr, vm_size_t len,
pmap_pv_insert_pde(dst_pmap, addr, srcptepaddr,
PMAP_ENTER_NORECLAIM, &lock))) {
*pde = srcptepaddr & ~PG_W;
pmap_resident_count_inc(dst_pmap, NBPDR / PAGE_SIZE);
pmap_resident_count_inc(dst_pmap, NBPDR /
PAGE_SIZE);
atomic_add_long(&pmap_pde_mappings, 1);
} else
dst_pdpg->wire_count--;
@ -6453,58 +6450,54 @@ pmap_copy(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_t dst_addr, vm_size_t len,
src_pte = (pt_entry_t *)PHYS_TO_DMAP(srcptepaddr);
src_pte = &src_pte[pmap_pte_index(addr)];
dstmpte = NULL;
while (addr < va_next) {
pt_entry_t ptetemp;
for (; addr < va_next; addr += PAGE_SIZE, src_pte++) {
ptetemp = *src_pte;
/*
* we only virtual copy managed pages
* We only virtual copy managed pages.
*/
if ((ptetemp & PG_MANAGED) != 0) {
if (dstmpte != NULL &&
dstmpte->pindex == pmap_pde_pindex(addr))
dstmpte->wire_count++;
else if ((dstmpte = pmap_allocpte(dst_pmap,
addr, NULL)) == NULL)
goto out;
dst_pte = (pt_entry_t *)
PHYS_TO_DMAP(VM_PAGE_TO_PHYS(dstmpte));
dst_pte = &dst_pte[pmap_pte_index(addr)];
if (*dst_pte == 0 &&
pmap_try_insert_pv_entry(dst_pmap, addr,
PHYS_TO_VM_PAGE(ptetemp & PG_FRAME),
&lock)) {
if ((ptetemp & PG_MANAGED) == 0)
continue;
if (dstmpte != NULL) {
KASSERT(dstmpte->pindex ==
pmap_pde_pindex(addr),
("dstmpte pindex/addr mismatch"));
dstmpte->wire_count++;
} else if ((dstmpte = pmap_allocpte(dst_pmap, addr,
NULL)) == NULL)
goto out;
dst_pte = (pt_entry_t *)
PHYS_TO_DMAP(VM_PAGE_TO_PHYS(dstmpte));
dst_pte = &dst_pte[pmap_pte_index(addr)];
if (*dst_pte == 0 &&
pmap_try_insert_pv_entry(dst_pmap, addr,
PHYS_TO_VM_PAGE(ptetemp & PG_FRAME), &lock)) {
/*
* Clear the wired, modified, and accessed
* (referenced) bits during the copy.
*/
*dst_pte = ptetemp & ~(PG_W | PG_M | PG_A);
pmap_resident_count_inc(dst_pmap, 1);
} else {
SLIST_INIT(&free);
if (pmap_unwire_ptp(dst_pmap, addr, dstmpte,
&free)) {
/*
* Clear the wired, modified, and
* accessed (referenced) bits
* during the copy.
* Although "addr" is not mapped,
* paging-structure caches could
* nonetheless have entries that refer
* to the freed page table pages.
* Invalidate those entries.
*/
*dst_pte = ptetemp & ~(PG_W | PG_M |
PG_A);
pmap_resident_count_inc(dst_pmap, 1);
} else {
SLIST_INIT(&free);
if (pmap_unwire_ptp(dst_pmap, addr,
dstmpte, &free)) {
/*
* Although "addr" is not
* mapped, paging-structure
* caches could nonetheless
* have entries that refer to
* the freed page table pages.
* Invalidate those entries.
*/
pmap_invalidate_page(dst_pmap,
addr);
vm_page_free_pages_toq(&free,
true);
}
goto out;
pmap_invalidate_page(dst_pmap, addr);
vm_page_free_pages_toq(&free, true);
}
if (dstmpte->wire_count >= srcmpte->wire_count)
break;
goto out;
}
addr += PAGE_SIZE;
src_pte++;
/* Have we copied all of the valid mappings? */
if (dstmpte->wire_count >= srcmpte->wire_count)
break;
}
}
out: